Method of operating induction-motors.



B. G. LAMME.

METHOD OF OPERATING INDUCTION MOTORS.

APPLICATION FILED JULY 6, 1908.

1,074,1 25, Patented Sept. 30, 1913.

Fly. 1. 3.

WITNESSES:

- AiTORNEY UNITED STATES PATENT OFFICE.

BENJAMIN G. LAMME, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR, BY MESNE AS-SIGNMENTS, 'IO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, OF EASTPITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

METHOD OF OPERATING INDUCTION-MOTORS.

Specification of Letters Patent.

Patented Sept. 30, 1913.

Application filed July 6, 1908. Serial No. 442,221.

T 0 all whom it may concern:

, Be it known that I, BENJAMIN G. LAMME, a citizen of the United States,and a resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvementin Methods ofOperatingInduction-Motors, of which the following is a specification.

My invention relates to induction motors, and it has for its object toprovide a method of starting or operating polyphase induction motorsthat obviates the necessity for employing auto-transformers inconnection therewith.

Figure l of the accompanying drawings is a diagrammatic View of a motorand a controller adapted for practising my invention, and Figs. 2, 3, 4and 5 are diagrams illustrating the connections of themotor Windings forthe various positions of the controller. v

' The motor comprises a secondary member 1, of the squirrel-cage orother suitable type, and a primary Winding divided into six sections 2,3, 4, 5, 6 and 7, two for each phase, the sections 3, 4 and?) beingconnected 1n star arrangement with their terminals connectedrespectively to contact terminals 8, 9 and 10 of the controller. Theremaining sections of the primary winding are connected, respectively,between dilierent pairs of contact terminals of the controller in such amanner that when the contact terminals engage the movable contactsegments of the controller along the broken line a, the sections of eachphase of the winding will be connected in series relation. The relationwill be better understood by traging the circuit through one phase ofthe winding, which is by way of devices bearing reference characters 11,12, 13, 7, 14, 15, 10 and 6, the circuits for the other phases of thewinding being similar thereto. In the position b of the controller,section 7 of the primary-winding of the motor is. removed from circuit,the outer terminal of the section 6 being then directly connected to thedistributing circuit, as shown in Fig. 3, and as will be understood bytracing the circuit through devices bearing reference characters 11, 16,10 and (3. In passing from position b to position 0 of the controller,section 2 of the primary winding of the motor is also removed fromcircuit and the outer terminal of the section 3 is connected directly tothe distributing circuit. In the position ofthe controller, sections 3,4 and 6 of the primary winding of the motor are connected in stararrangement directly to the distributing circuit and the sections 2, 5and 7 are also connected in star arrangement directly to thedistributing circuit, the two sets of star-connected sections beingentirely independent of each other, this latter arrangement being shownin Fig. 5.

\Vith the arran ement shown in Fig. 2, the torque exerteisap-proximately 25% of the normal torque of the motor; namely, thatobtained with the arrangement shown in Fig. 5, since it is equivalent toapplying one-half of the normal voltage tothe motor. With thearrangement shown in Fig. 3, from 35 to 40% of the normal torque of themotor is obtained, and with that shown in Fig. 4 from 65 to of thenormal torque is obtained. Although, with the latter two arrangements,some unbalancing of the currents in the several phases of the windingoccurs, it has been found that the torques exerted are only slightlyreduced on that account. In practice, it may be unnecessary orundesirable to provide as many gradations in the starting torque of themotor as are provided for in Fig. l, and for that reason either of thearrangements that give unbalanced conditions may be omitted.

I claim as my invention:

1. The method of starting a polyphase induction motor having a. primarywinding comprising a plurality of sections for each phase of currentwhich consists in first making a supply-circuit connection for eachphase of current, with the sections corresponding to a plurality ofphases connected in series relation, then successively cutting out asection corresponding to each of a plurality of phases, and finallyconnecting one terminal of each section to the supply circuit and theremaining terminals ofthe respective sections to force two independentgroups.

2. The method of Starting a polyphase in duction motor having a primarywinding comprising a plurality of sections for each in testimonywhereof, I have hereunto phase of current which consists in firstconsubscribed my name this 30th day of June,

necting the sections corresponding to each phase in series relation,then cutting out a 1908. section or sections corresponding to one orBENJ. G. LAMME. more phases, and finally connecting the Witnesses:

sections in two independent star-connected 1 ELIZABETH LIVINGSTONE,

groups. l BIRNnY HINEs.

It is hereby certified that in Letters Patent No. 1,074,125, grantedSeptember 30, 1913, upon the application of Benjamin G. Lemme, ofPittsburgh, Pennsylvania, for an improvement in Methods of OperatingInduction-Motors, an error appears in the printed specificationrequiring correction as follows: Page 1, hne 100, for the word forceread form; and that the said Letters Patent should be read with thiscorrection therein that the Same may conform to the record of the casein the Patent Oflice. I

Signed and sealed this 28th day of October, A. D., 1913.

[SEAL-1 THOMAS EWING,

Commissioner of Patents.

